1. Field of the Invention
The present invention relates to a pressure treatment roller. More specifically, the present invention relates to a pressure treatment roller that may be used to treat, for example, non-woven webs, textile material webs, webs of paper, webs of card material, plastic films or metal foils. The pressure treatment roller has a roller core and a casing tube. The casing tube is supported on the roller core by a central support. A first intermediate space and a second intermediate space are disposed on both axial sides of the central support.
2. Discussion of the Related Art
Pressure treatment rollers per se are known from, for example, German reference DE-A 17 85 197. Pressure treatment rollers interact with a counter roller to form a roller gap or nip between the two rollers. A web of material is guided and squeezed (i.e., treated) through the nip. When treating a web of material, it is an object to achieve as uniform a treatment of the web as possible over the entire width of the roller. Thus, it is desirous to apply as uniform a pressure as possible to the web over the entire width of the roller.
German reference No. DE-A 14 60 290 discloses a roller where the casing tube is supported exclusively at the center of the casing tube. The casing tube is supported on the roller core over as small a part of its length as possible. Thus, the central support is designed as a supporting disk 5. Reinforcing rings 6 are distributed over the length of the casing tube, but these reinforcing rings 6 do not contact the roller core even when the casing tube is deformed during normal use, as shown in FIG. 3 of the German '290 reference.
These types of pressure treatment rollers are known in the art as uncontrolled or "passive" deflection adjustment rollers because their structural design enables them to essentially adapt to the bending line of their counter roller.
"Active" deflection adjustment rollers use hydrostatic supporting shoes to support the roller casing on a yoke. Alternatively, active deflection adjustment rollers use a floating roller. A hydraulic fluid occupies half of the hollow space inside of the roller to support the floating roller.
In an active deflection adjustment roller, it is possible to control the temperature of the roller's outer surface by heating or cooling the hydraulic fluid. The hydraulic fluid transfers (or dissipates) heat to (or from) the roller casing, so that the surface of the roller can be controlled to have a predetermined temperature. Thus, the web of material can be treated at a predetermined pressure and at a predetermined (i.e., increased or reduced) temperature. But it is preferred not to use the same hydraulic fluid to support and heat the roller casing.
In conventional passive deflection adjustment rollers there is no hydraulic medium available to use to control the temperature of the roller.